Generally, a heat exchanger is provided with multiple tubes which are stacked, and two header tanks which are respectively arranged at two longitudinal-direction ends of the tube, for example, referring to JP-2005-30741A.
In this case, one of the header tanks has therein an inlet side passage and an outlet side passage. A flow dividing plate is arranged in the inlet side passage to flow-divide refrigerant (having been introduced) into the portion (of inlet side passage) near an inflow port of the inlet side passage and the longitudinal-direction inner portion of the inlet side passage, in order to restrict an uneven flow of refrigerant at the portion near the inflow port and the longitudinal-direction inner portion of the inlet side passage. Thus, refrigerant can be evenly shunted to flow into the multiple tubes which are stacked in the longitudinal direction of the header tank.
Referring to U.S. Pat. No. 6,973,805-B2, a round inflow port is arranged at the upstream end of the inlet side passage, and covered by a fluid-dispersing member which has a spherical surface shape and is provided with multiple small holes. Fluid which is issued through the small holes flow upwards and downwards due to the spherical surface of the fluid-dispersing member. Thus, a refrigerant dispersion effect is improved.
However, in the case of JP-2005-30741A, fluid is evenly shunted to flow into the tubes in a limited flow amount range of refrigerant. It is significantly difficult to set the suitable arrangement position and the suitable length of the flow dividing plate for the even flow of refrigerant into the multiple tubes, with respect to a large flow amount range of refrigerant, for example 30-180kg/h.
In the case where the refrigerant flow amount is large, refrigerant easily flows to the longitudinal-direction inner portion of the header tank. Thus, the flow dividing plate is located away from the inflow port, and the length of the flow dividing plate is to be shortened. On the other hand, in the case where the refrigerant flow amount is small, refrigerant relatively easily flows downwards to the portion near the inflow port of the inlet side passage. Thus, the flow dividing plate is arranged near the inflow port, and the length of the flow dividing plate is to be enlarged. Therefore, it is difficult to evenly flow-divide refrigerant with respect to a large flow amount range of refrigerant.
Moreover, U.S. Pat. No. 6,973,805-B2 fails to teach in detail the diameter of the small hole formed at the fluid-dispersing member. In the case where the diameter of the small hole is set about 1 mm, for example, the pressure loss of refrigerant will increase when the refrigerant flow amount is large. Thus, the efficiency of the refrigerant cycle system is decreased.
Moreover, referring to FIGS. 5A and 5B of U.S. Pat. No. 6,973,805-B2, it is also described that only the lower half portion of the round inflow port is coved by a fluid-dispersing member, which has a semi-spherical surface shape and is provided with multiple small holes. In this case, the flow-dividing ratio of refrigerant between the upper half portion and the lower half portion of the inflow port is about 200:1. That is, most of refrigerant flows through the upper half portion of the inflow port into the header tank. Thus, it is difficult to evenly flow-divide refrigerant in a large flow amount range.
Furthermore, referring to FIGS. 7A and 7B of U.S. Pat. No. 6,973,805-B2, it is also described that multiple small holes are arranged around the round inflow port. In this case, the flow-dividing ratio of refrigerant between the inflow port and the small holes is about 100:1. That is, most of refrigerant flows into the header tank through the inflow port which has a relatively large opening. Thus, it is difficult to evenly flow-divide refrigerant in a large flow amount range.